Brief Summary

Introduction

Its name might be “major,” but the spider known as Dictyna major is only about 2.5-3.5 millimeters (0.1-0.14 inches) long (5,9)! This dull-brown spider (7) with a light line going through its cardiac mark (the marking on its abdomen over the heart(13))(9) shares many features with other spiders in the family Dictynidae, such as a relatively wide abdomen and short legs(9). In fact, in some places in North America(2,3,10,15), it’s extremely difficult to tell the difference between this spider and the spider Dictyna coloradensis(10,15). Dictyna major is native to many northern locations, including Canada(4,6), Alaska(12) and other parts of the western United States(4,6,10,15), a large portion of Europe(4,14), and part of northern Asia(6); its range extends north as far as Disko Island in Greenland(9) and northern Russia(6). Throughout its wide range, it can be found in a variety of habitats, from grasslands(10) to sandy shores(14), and it builds its webs (adding to them over a period of time(10) in many different locations, such as grass(12), flowering plant stalks(10), shrubs(9), or rocks(9). Like those of some other groups of spiders(11), these webs are made in part of an ancient type of silk known as cribellate silk(1,8,15), each thread of which contains hundreds or even thousands of tiny fibers which snag insects without using any gluey liquid(1,11). In the western United States, though, the insect-catching of Dictyna major—as well as that of Dictyna coloradensis—is sometimes problematic. In some areas there, insects are used to control the dangerous spread of invasive plant species such as spotted knapweed (Centaurea maculosa) and yellow starthistle (Centaurea solstitialis)(15). As the stalks of these weeds are an especially good habitat for these spiders, the spiders multiply in grasslands invaded by these plants(10), and when they capture the insects intended to eat the weeds, they make the problem of controlling the weeds even harder to solve(15). So, although it’s small(9,10), Dictyna major can indeed be of major importance!